CA1124490A - Method and apparatus for cooling and neutralizing acid gases - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A process and apparatus for neutralizing hot acid gases is disclosed. Prior to neutralizing the gas, it is intro-duced into a zone, e.g., a cyclone to establish an upwardly, generally spiral gas stream. This gas motion permits removal from the gas of larger particles which concentrate at the cyclone wall by centrifugal forces. The upwardly-moving gas stream which may or may not have a spiral motion is contacted with an upwardly-moving spray of a basic neutralizing liquid or slurry under con-ditions such that the spray droplets moderately overcome gravi-tational forces such that they experience a sufficiently long residence time in the cyclone to be evaporated to dryness. The product gas from the cyclone then can be treated further to re-move small particles and salt product.

Description

I

METIIOD AND APPAR~TUS FOR COOLING ~Nn N~UTR~LI~IN~ ~CID ~S~S

BACK~ROUND OF THE INV~NTION
This invention relates to a method and apparatus for ¦ cooling and neutralizing acid gases which utilizes a step of contacting the gas with a liquid spray.
The problems of emitting to the atmosphere industrial gases containing a high proportion of noxious substances have long been recognized. Acid gases such as the sulfur oxides, nitrogen oxides and the hydrogen halides are particularly common and undesirable components of industrial effluent gases. Bled to the atmosphere; such gases condense on water droplets forming strong acids and, blown about by wind, such droplets cause severe corrosion of metal parts and machinery even many miles from the industrial site. The direct danger to animal and vegetable life in such areas has been established. As a result, local ordinances and national regulations in the United States and various other countries have set increasingly strict limits on the pèrmissible acid gas-content of effluent gases. A variety of methods have been proposed for dealing with this situation, but none has so far been wholly successful in dealing with the tri-partite problem of handling large volumes of hot effluent gas containing comparatively high concentrations of acid gases, reducing acid gas content to an acceptable level, and still maintaining an economical operation.

DESCRIPTION OF PRIOR ART
It has long been known to purify gas streams through contact with a solid sorbent material capable of selectively reacting with and/or physically sorbing the impurities from 44~0 the gas strcam. Sorptive materials were commonly employcd in the form of filter cakes or beds of granular material as taught, for example, by U.S. Pat. Nos. 2,391,116, 2,526,776 and 3,197,942.
~owever, many problems were associated with such methods. Packed sorption towers of the types heretofore employed were restricted in their use to the treatment of relatively small volumes of gaseous material. Larger volumes could not be efficiently pro-cessed through fixed bed towers because of the large pressure drop that occurs across the packing. The need ~or large amounts of power to force the gas through the beds made such processes ; uneconomical when the contaminant gas was present in concentra-tions below about 400 parts per million. Moreover, fixed bed I towers experienced the problems of having "break~through" point, that is, the bed of sorbent material would gradually become sat-¦ urated until, at a particular point, the level of efficiency would rapidly fall off. At this stage, a break-through of con-taminants would occur and pollutants would escape until the sys-tem was either shut down and changed or the gas stream directed to a freshly packed tower. This was, quite simply, a batch oper-ation. The serious problems of pressure drops, break-through points and discontinuous operations were found to exist in fluid-ized bed operations, such as that shown by U.S. Pat. No. 3,723, 598, where the granular sorptive materials in a bed are agitated ; by the entering contaminated gas stream so that the aerated mass has a tendency to behave more as a fluid.
U.S. Pat. No. 2,919,1i4 discloses a process for re-moving fluoride contaminants from gas streams which avoids the high pressure drops and break-through points of certain of the prior art processes described above. This process consists of dispersing finely divided caIcium carbonate (CaCO3) or other basic salts of alkaline or alkaline earth metals in the gas stream containing fluoride contaminants and directing the parti-cle-laden stream into a baghouse filter where a permeable~layer of the alkaline material is allowed to build up. Ilowever, this process is deficient in other aspects in that it is limited to : alkaline su~stances which will react with fluoride gases in the dry state. Furthermore, this process requires that a layer of the alkaline material be built up on the inside of the filter ; surface be.ore it can become effective.
"Wet processes" are known in the prior art in which a tower is filled with a packing material and a liquid, such as water, through which a contaminated gas stream is passed. Wet washing of waste gases with aqueous solutions or slurries of Manganesesulfate, calcium bicarbonate, lime, ammonia and sodium sulfite-bisulfite to remove sulfur dioxide was discounted in U.S.
Pat. No. 3,551,093 as impractical because of the necessity of cooling the flue gas to below 100C. (the boiling point of water) : befo~e sorption would take place. Furthermore, the high pressure drop across the packed tower and comparatively slow rate of dif-fusion of the gas through the liquid phase make this process impractical for large-scale operations.
It has also been proposed to simultaneously cool and neutralize a hot acid gas by contacting the gas with a spray of liquid droplets containing a neutralization agent. In these pro-cesses, the neutralization agent reacts with the acid gas to in-crease its pH to about 7. The quantity of water utilized in the spray or water-solid suspension is sufficient to reduce the gas temperature by evaporation of the water such that the reaction product and/or unreacted neutralizing agent is dry. Essentially complete dryness must be obtained otherwise an aqueous composi-~1.2~9V

tion will collect on the bottom of the apparatus utilized whichis corrosive and difficult to remove and which causes undesirable downtime of the equipment.
The apparatus utilized in this procedure generally is that used in spray dryers or in gas and liquid sprays, both pro-ceed downward in a concurrent manner. In some limited applica-¦tions, eountereurrent flow is utilized wherein the gas proeeeds j upwardly and the liquid spray proceeds downwardly. However, ¦this latter teehnique is generally undesirable since insuffi-eient residenee time of the aas and liquid spray in contact is aehieved to effect substantially complete neutralization while attaining substan~ially complete evaporation of the contacting ¦liquid. The p~oblem of substantially complete dryness is com-¦plicated by the fact that it is common for industrial emissions lS ¦ to contain particulate matter which also must be removed. If ¦the particulate concentrations are high, with loadings greater than about 0.5 grams/dscf, the particulates impact with the ¦liquid spray to cause spray conglomerations and the formation 1f larger droplets which are more difficult to evaporate.
! In forming the sprays sueh as with a single fluid ¦ nozzle or with two fluid nozzles or spinning discs, a size dis-¦ tribution of liquid partieles is ereated. The smaller droplets ¦evaporate rapidly while the larger droplets evaporate slowly.
¦ The size of the queneh reactor must be established to provide ¦ "safe" exposure times in order to achieve eomplete evaporation of even the larger droplets. Thus, the size of the apparatus has arown excessively while not eliminating the questions of reliability when nozzle or disc liquid droplet distributions ehange with time or operating conditions. For example, if the ~ diameter of apparatus utilized providee for a gaz veloeity ., '_5_ .' ` .

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~o~ 6 ft. pe sccond and a drop1et of 400 micron~ is formc<l, ~he initial downward velocity of the droplet is 6 ft. per second ¦plus the terminal velocity of 5 ft. per second or 11 ft. per second net. If the evaporation time is 6 seconds and the parti-; 5 cle size decreases to 40 microns at the dry state, the length of the quench reactor would necessarily be in the order of about 52 ft. Such an apparatus is expensive to build and maintain and is therefore undesirable.
It would be desirable to provide a means for neutral-izing and cooling acid gases at rates which are commercially attractive without the necessity of large apparatus. Further-; 1I more, it would be desirable to provide such an apparatus which ¦I gives substantially complete assurance that the gas is neutral-ized and the product gas composition is dry.

¦ SUMMARY OF THE INVENTION
~ In accordance with this invention, a gas stream con-¦ taining acid gases is caused to move in a generally spiral path I in a preliminary treatment zone preceeding a reaction zone to ¦ remove relatively large particles which may be present in the ¦! acid gas. The acid gas, substantially free of these large par-ticles is introduced upwardly in a reaction chamber and is con-tacted therein with an upwardly moving liquid or slurry spray which reacts to neutralize the acid gases. The liquid or slurry spray particles experience a long residence time in the reactor because the initial upward velocity of the particles resulting ¦ from pressure at the spray nozzle and the force of the upwardly ¦ moving gas is counterbalanced by gravity forces in a manner such ! that the spray particles move slowly upward within the reactor until the water therein is evaporated. By controlling the aver-4~

age particle size in the spray and the velocity of the upwardlymoving gases, it is possible to achieve a substantial reduction in the size of the reactor thereby providing substantial econom-ic benefits. This invention can be incorporated as the first step or a final step in an integrated process for removing acid gases and particulates from a gas stream.

I
i BRIEF DESCRIPTION OF THE DRA~INGS
¦ ~ig. 1 is a cross-sectional side view of the reaction I chamber of this invention.
I Fig. 2 is a cross-sectional view taken along line 2-2 ¦of Fig. 1.
`I Fig. 3 shows the invention in an integrated process ¦ for removing acid gases and particulates from a gas stream.
15 ll ¦ DESCRIPTION OF SPECIFIC EMBODIMENTS
i Typically, the gas streams treated in accordance with this invention comprise effluent gas streams from a furnace or I smelter or the like. The effluent gas is introduced into a pre-¦ liminary treatment zone preceeding a reaction zone in a mannerto impose a spiral movement to the gas to permit removal of rel-atively large particles in the gas. The larger solid particles present in the effluent gas are forced outwardly from the center ¦ of the preliminary treatment zone by centrifugal forces and are collected in a small chamber having an opening on the inner wall : at the bottom of the treatment zone. By removing these larger particles, the formation of undesirably large liquid droplets generated by impact of a reactant spray with these particles is minimized or eliminated. The gas then is introduced in the bot-tom of a reaction chamber wherein it is contacted with the reac-~,~,Zi~O

; tant spray. The initial rotary motion of the gas stream ef-fected by introducing it tangentially into the prctre2tment zone dissipates as the gas passes upwardly from the pretreatment zone into the reactor wherein it contacts a liquid or slurry spray I which emanates from a nozzle positioned within the upwardly moving gas stream after the larger particles have been removed therefrom. ~hen the acid gas initially introduced into the re-action chamber is relatively free of larger particles, the spray I nozzle can be located at a vertical height at or near the point of introduction of the acid gas into the reactor. Alternatively, if the gas to be treated is free of larger particles, it can be introduced directly into the bottom of the reactor without a preliminary treatment step.
The present invention permits the use of a plurality of spray nozzles for introducing a plurality of reactant sprays ¦ into the acid gas. This is effected by utilizing a plurality of independent preliminary treatment zones wherein larger par-ticles are removed from the gas and wherein a spray nozzle is positioned in each zone ~ upstream of the reactor. Since the larger droplets em~nating from the nozzles travel a shorter dis-tance from the nozzles than do the smaller droplets, the forma-tion of large drops by impactation of the larger droplets from different sprays is eliminated. The use of multiple sprays is advantageous since it permits more complete gas-spray contact as compared with the use of a single spray. In prior art pro-cesses utilizing a downward flow of gas in a reactor, multiple spray nozzles are not used since large drops result from impac-` tation of droplets emanating from different nozzles. This leads to undesirable accumulation of corrosive aqueous compositions in the bottom of the reactor.

I . 1, o I While it is desirable to form a liquid or slurry spray having a uniform droplet size, in practice the size of the drop-let varies over a relatively wide range. In the instance of the prior art, the larger droplets initially moved downward would pass through the entire length of the reactor without becoming completely evaporated and would collect on the bottom thereby causing damage to the reactor. In contrast, in the present in-vention, such droplets experience a higher residence time within the reactor since the effect of gravitational orces thereon is opposite to the gas entrainment velocity and they thereby become evaporated. The smaller particles which require less residence time to become evaporated experience shorter residence time.
However, in any event, all of the droplets become evaporated prior to exit. Thus, in essence, the larger the droplet size of dispersion due to malfunctioning of a spray nozzle, the safer the system of this invention becomes.
The temperature of the gas may range from about 150~F
to 3000F or hi~her, although typically the temperature ranges from 250F to 1000F. The flow rates may vary from as little as 1 cc/min to more than 1 million cfm and is limited only by the size and design of the reaction chamber. The gaseous contami-nants will vary dcpending on the particular industrial operation.
For example, fertilizer, aluminum and secondary aluminum opera-tions generate large volumes of hydrogen fluoride and silicon tetrafluoride. Coking operations produce quantities of sulfur dioxide and lesser amounts of the nitrogen oxides. Hydrogen chloride is another by-product in the secondary aluminum process as well as in the demagging of primary aluminum in the inciner-: ation of waste chlorinated hydrocarbons and in municipal incin-erators.

~3.~'~4~0 The gas stream will typically also contain entrained ¦particulates which may consist of dust, uncombusted carbon, various metallic oxides such as silica, alumina, fcrrites, etc.
In refinery operations, cntrained droplets oi liquid hydrocar-I bons and derivatives may also be found in the effluent gas ¦ stream.
The gas stream is directed into the reaction chamber where it comes into contact with a solution or slurry of a basic material, that is, a compound or substance which has a basic reaction in water. The most common materials of this type are the alkali and alkaline earth metal oxides, hydro~ides, carbon-ates and bicarbonates, but the invention is not limited to these.
Specifically included within the scope of this invention are: i NaOH, Na2C03, NaHC03, Na2S03; KOH, K2C03, KH~03, K2S~3; LiOH, Li2C03, LiHC03; Ca(OH)2, CaO, CaC03; Mg(OH)2, MgO, MgC03; Ba(OH)2, BaO, BaC03; Zn(OH)2, ZnO, ZnC03; Ni(oH)2, ~iO, NiCo3; Cu(OH)2, CuOH; Fe(OH)3, Fe203, FeC03, Fe2(C03)3. Also included in this 1 invention are the various ores which may comprise one or more ; ~ of the above compounds and have a basic reaction in water. Ex-emplary of such ores are nepheline syenite and phono'ite. c ¦ All of the above-mentioned alkali metal compounds, ¦ those of sodium, potassium and lithium, are very soluble in I ! water and may be employed as an aqueous solution. The other t~
¦ basic compounds listed above range from sparingly scluble in 25 ¦ cold water to virtually insoluble. These compounds may be em- ,~
ployed in finely-divided form as aqueous slurries. Slurries of calcium and magnesium compounds can be utilized economically j in the present process. Althou~h the solutions and slurries ¦ are typically employed at or about room temperature, in the case ¦ of a basic material of borderline solubility, it may be desirable !

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to employ a hcatcd solution to keep the material i~ solution and thereby avoid the clogging problems which frequently accompany thc use of slurries. In instances where the tcmperature is be-low about 250F, particularly wherc the temperature is below the boiling point of water, it is desirable to superheat the so-lution or slurry. For example, by heating under pressure, the liquid temperature can be raised to about 1000F to insure thcre ; is adequate heat in the reaction chamber to completely and in-stantaneously vaporize all of the liquid and to leave a dry salt reaction product. However, it is preferred, and in most indus-trial operations it will bc the case, that the heat supplied by the gas stream itself be adequate. Therefore, for convenience in this description of the invention, the gas stream will be re-ferred to as a hot gas stream.
: 15 Upon contact between the hot gas stream and the aqueous solution or sl~rry, a somewhat violent reaction occurs.
The water is vaporized cooling the gas stream, causing great turbulence and facilitating intimate contact between the acid gases and the basic material. An acid mist is created adjacent the spray nozzles because of the saturated environment and the ¦¦ high dew point of acid gases. This effects a longer residence time of the acid gases in the mistarea adjacent the nozzles thereby resulting in more complete neutralization of the acid ¦ gases with the formation of the corresponding acid salts. Under ¦ the described conditions the reaction is quite rapid and thc ¦ necessary residence time of the gas in the reactor ranges from ¦ about one millisecond to not mo~e than about 2 seconds.
I For e~ample, if a lime slurry i~ used to quench a gas ¦ stream containing hydrogen chloride, the produce will be the ¦ salt calcium chloride (CaC12). The concentration of the basic I
., ~ ' .

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~¦ material in the aqueous solution or slurry and the relative pro-¦portion of hot effluent gas to solution or slurry are variablcs which can be adjusted so as to insure that there is a stoichio-I metric equivalent or excess of basic material in the reaction ¦ chamber at any given time and for all the water to be evaporated I to form a "dry" product gas. For example, for a given flow rate ¦ of effluent gas having a given c~ncentration of acid gases, onecan calcul~te by conventional means the necessary rate of addi-tion of basic material to provide a stoichiometric equivalent or excess. Based on the flow rate and temperature of the effluent gas, one can also compute the volume of water or aqueous solution which can be heated and vaporized by the gas stream. Leaving a ¦ certain margin of error to account for inefficient thermal con-tact, a suitable liquid flow rate may be chosen. The concentra-lS ¦ tion of basic material in the solution or slurry necessary to I provide the previously calculated rate of addition of basic ma-: terial is then determined. If the liquid flow rate is increased, not to exceed the rate at which the liquid can be heated and com-¦ pletely vaporized, the concentration of basic material can be ¦ correspondingly decreased.
Upon leaving the reaction system of this invention, ~¦ the gas stream typically is at a temperature of about 100-5000F
¦ and is substantially free of acid yases. The acid salts Lormed in the reaction chamber are entrained with the neutralized gas stream and are treated in a manner described below.
In one aspect of this invention, the initial effluent gas stream is directed to a manifold from which a plurality of smaller effluent yas streams are formed. Each effluent gas stream is directed into a separate initial treatment section in 30 ¦ which the cy onic motion of the gas stream is initiated and :~.Z44~30 the larger p ticles are separated therefrom. In each of these initial sections, the hot gas is contacted with a spray of liquid ; or slurry to neutralize the acid gases therein. Opera~ing in this manner permits increasing the capacity of a given reaction system and has the additional advantage of utilizing a plurality of liquid or slurry sprays independent from each other. This ; ~minimizes or prevents large drople~ formation due to impaction of liquid or slurry droplets emanating from different nozzles while increasing reaction efficiency resulting from the improved liquid-gas contact.
This invention now will be described with reference ~o the accompanying drawings. The reactor 10 includes a main reac-tion chamber 12 and a plurality of initial reaction chambers 14, 16, 18 and 20. The efiluent gas S1 is introduced into manifold 24 having three internal walls 25, 26 and 27 thereby providing ~ entrances 28, 30 and 32 respec~ively to reactors 14, 16, 18 and,~ 20. Since the effluent gas is introduced into each initial reac-tor tangentially to the inside wall ~hereof, the introduced yas moves tangentially on the inner wall of each initial reactor in `'! 20 a cyclic motion and the larger particles in the gas migrate to-ward the wall and are collected in conduits 34, 36, 38 and 40.
The upwardly moving gas streams r~presented by arrows 42 and 44 contact a spray of liquid or slurry of a basic material which emanates from spray nozzles 46 and 48 which are located within the venturics 66 and 68. As shown, the spray nozzles 46 and 48 comprise a two fluid spray each having a conduit 50 or 52 for introducing a gas such as air under pressure and a conduit 54 or 56 for introducing the basic liquid or slurry. The air and liquid or slurry are mixed at the exit of the nozzle 58 or 60 and pass into the gas streams 42 or 44 and droplets havin~ a size .
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generally within the range of about 20 microns to about 200 mi-crons. In order to attain the desired average droplet size and to achieve an initial upward spray velocity wiLhin the range of abou~ 2 to lO ft!sec, preferably about 3 to 6 ft/sec, the nozzle pressure is maintained between abouL 40 to 200 psig, preferably 1 40 to 70 psig. Each of the spray nozzles 46, 48, 62 and 64 are ¦ vertically adjustable within their respective initial reaction ¦ chambers so that the contact time between the spray and the up-¦l wardly moving gas within the overall reactor 10 can be adjusted I as desired. Generally, it is preferred that the head of the noz-zles be positioned at or near the venturi section in each of the initial reactors.such as venturi sections 66 and 68. By opera~ing in this manner, the spray and gas are initially contacted after ll the larger particles have been removed from the gas and the re-~ spective sprays are independent Or each o~her thereby minimizing ¦ large droplet formation due to droplet agglomeration. The re-spective sprays and hot gas then move into the main reaction ¦ chamber 12 wherein acid gas neutralization is rendered substan-I tially complete.
¦ Referring to Fig. 3, this figure illustrates a typical I integrated process for abatiny acid gases from an effluent yas ¦ stream according to the present invention. The exit stream S2 from reaction chamber 10 is directed downstream via conduit 101 to a mixing area 103 (shown in dotted ou~line) where a particu-late material capable of sorbing the residual acid yases isblown or otherwise introduced into the gas stream. Although described herein as an "area" for purposes of discussion, it is not necessary that this be a definable structure per se. The particulate material may be blown or otherwise introduced into the gas stre n at ont or more points along the conduit 10l down-1~ -14-44~) stream from reaction chamber 10 in ~n amount sufficient to sorb the residual acid gases. A preferred means of adding the paticulate material is by gradually feeding it from a container 105 into a conduit 107 and mixing it with secondary air intro-duced via conduit 109 to suspend the particles. The mixed particle-air stream is then directed via conduit 111 into the throat of a venturi 113 installed in conduit 101.
Especially preferred sorptive materials for this : process are nepheline syenite and phonolite. The use of nepheline syenite to sorb small residual amounts of acid gases from a high-volume effluent gas stream is described in more detail in U. S. Pat. Nos. 3,721,066 and 3,808,774. The afore-mentioned U. S. Pat. No. 3,808,774 directed to the in situ ' water activation of nepheline syenite is especially relevant to the present invention.
In particular, U. S. pat. No. 3,808,774 describes a process for the abatement of acid gas emissions on the order of 100-500 ppm. from a hot effluent gas stream by the ste~s of:
1) quenching the gas stream with water to cool and humidify it; 2) introducing to the gas stream particulate nepheline syenite having a particle size of about 5-20 microns to sorb both moisture and acid gases therefrom, and 3) directing the gas stream bearing the ~epheline syenite particles into a baghouse filter to remove the particulates together with the moisture and acid gases sorbed thereon.
As noted above, the gas stream S2 leaving reaction chamber 10 is typically at a temperature of about 100 -500 F
and humidified; the residual acid gas content is on the order of 100-500 ppm. Thus, the gas stream is ideally suited for the practice of the aforementioned process. In accordance therewith, the I1 3.i.2~4~0 humid gas s~r am is oper~tive to wet the particulate nepheline syenite and thereby activate it to promote the selec~ive soLption of acid gases. The activation and sorption occurs quite rapidly and is ideally completed by the time the gas strcam and entrained ll nepheline syenite reach the means for separating Lhe ~ar~iculatcs.
The rate of activation Or nepheline syenite appears to be at ~¦ least in part dependent on the relav~ive humidity of the gas ¦ stream; and at a relative humidity of 20-30~ or hiyher, the acti-li vation time is on the order of 1 millisecond. Although the acti-vation time is reduced still further at higher relative humi~ities, ' ordinarily in the sorption process the amount of water introduced into the gas stream in chamber 10 is controlled so that the rela-tive humidity of the stream S2 does not exceed about 50~. The reason for this is that at higher relative humidities some clog-ging of the entrained particulates tends to occur along the flow-path and particula~ly in the baghouse filter. Once activated, particulate nepheline syenite sorbs acid gases from the gas stream in about 0.01-3.0 seconds.
This method of abating residual acid gas emissions has been shown to be about 95-99~ effective as well as economical in removing acid gases present at concentrations of about 100-500 ppm. Because this sorption process is essentially a surface ¦I phenomenon, only a comparatively small portion of the total par-ticulate material on the order of 7-15 wt. ~ is actively used;
and it is not economical to employ this process at higher con-centrations of acid gases. The fact that only 7-15 wt. ~ of the particulate material is available for sorption of acid gases must be taken into account in calculating ~he rate of addition I of the particulate material necessary for approximately a stoich-iometric equivalence based on the concentration oE acid gases ~ .2~

and flow rate of the gas stream. Ilowever, by first cmployingthe quenching-reaction step which utilizes essentially all of the basic material to remove ~he bulk of the acid gases, the morc Iselective and efficient sorption step becomes economical for cleaning up acid gas residuals. The overall effectiveness of the I first stage, the reaction chamber-quenching process, and the se-cond stage, the introduction of particulate nepheline syenite or similar material, in abating acid gas emissions is as high as I 99-9%
I A preferred means of separating the gas stream Erom the particulate matter entrained therein is the USê of a bay-house filter 115 ~s described in the aforementioned U.S. Pat.
No. 3,808,774. The fact that residual acid gases and some mois-j ture are removed from the gas stream due to sorption by the par-lS ticulate material prior to reachiny the baghouse filLer means ; that corrosion of the ilter is minimi~ed. The reduction of moisture in the gas stream is also important in reducing fogging or misting conditions near the gas stream outlet. Moreover, the I baghouse filter 115 removes not only the particulate nepheline 1 syenite or similar material with moisture and acid gases sorbed l thereon, but also removes the entrained salt particles from the ¦ first stage treatment and other particles which were initially present in the effluent gas. Therefore, on leaving the bag-~ house, the exit stream S4 generally will be roady for venting to the atmosphere.
As previously noted, the nepheline syenite, phonolite or similar material employed in the sorption step of this mode of practicing the integrated process may also be used as the basic material for the quenching-reaction step. The use of nepheline syenite, phonoli~e or similar natural ore as the basic ¦material in the first stage as well as the sorptive material in the second stage of this process is particularly efficacious in the glass-making industry.
The salt by-product from the first stage and the ; 5 particulate material with acid gases sorbed thereon collected in the baghouse may be combined and recycled directly into the ¦ glass-making furnaces. The high temperature in the furnaces promotes the decomposition of the ore-acid gas reaction product thereby regenerating the ore and the acid as raw materials for ~ 10 the glass-making operation.

; EXAMPLE I
This example illustrates that this invention provides ` ~ substantial reduction in reactor size without adversely affecting the desired neutralization process.
The data in Table I illustrate the comparison of the cocurrent upward flow process of this invention with the conven-tional cocurrent downward flow process.
In a typical neutralization process, the incoming hot acid gases are at a temperature of about 1000C while the largest spray droplet size is about 400 microns. The initial velocity of the spray from the nozzle is about 6 ft/sec while the terminal droplet velocity due to gravitational forces is about 5 ft/sec.

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4S~) The data in Table I show that this invention permits ¦utilizing a much smaller reacto:r to attain the same degree of .¦dryness as obtained with a cocurrent downward flow reactor.
¦Furthermore, in the upward flow reactor of this invention, the ¦ larger droplets experience a longer residence time in the reac-.~tor than do the smaller droplets thereby improving the overall :Idryness of the product gas while in the downward flow reactor, :~the residence time in the reactor for the larger droplets is less than that of the smaller droplets. Thus,.the probability ¦of liquid entering downstream treatment steps is much higher in ~the downward low reactor.

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Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for treating an effluent gas which gas contains acidic components of varying particle size which comprises:
(a) a first chamber having an inlet and an outlet, the outlet being positioned above the inlet, the chamber being configured as a truncated cone, the inlet in communication with the base of the chamber and substantially perpendicular to the longitudinal axis of the chamber, the inside walls of the chamber sloping upwardly and inwardly whereby the effluent gas introduced into the first chamber moves upwardly in a spiral path within said chamber effecting removal of the larger particles from the gas;
(b) a particle collection means disposed below the base of the first chamber to receive the particles removed in the first chamber;
(c) a second cylindrical-shaped chamber downstream of the first chamber and in communication therewith, the chamber configured to cause the gas to flow in an upward direction;
and being free of structural interference from one end to the other;
(d) adjustable spray nozzle means to introduce a spray of a basic material in a direction cocurrent with the upwardly moving effluent gas, said means including a discharge end, said end positioned at the apex of the first chamber such that the stream contacts the effluent gas after it has followed its spiral path and flowed into the second chamber; and to control the residence time and to cause reaction of the basic spray and acidic components while the spray and the acidic components move upwardly in the second chamber to evaporate substantially all of the spray; and to form a dry stream with entrained acid salts, the dry stream exiting from the chamber being substantially free of acid gases;
(e) means for removing products of said reaction from the effluent stream after the stream has left the chamber.

2. The apparatus of Claim 1 including venturi disposed between the means for introducing the spray and the second chamber.

3. The apparatus of Claim 2 including a plurality of first chambers each having a nozzle for introducing the spray and means for directing a portion of said effluent gas to each of said chambers.

4. The apparatus of claim 1 including a plurality of said chambers each having a nozzle for introducing the spray and means for directing a portion of said effluent gas to each of said chambers.